feat: rental drafts, room modal cleanup, tariff auto-code

- New hotels get 3 rental object templates (tennis/sauna/conference) as drafts (is_active=false)
- RentalPage: draft templates shown separately with Activate/Delete buttons
- Migration 047: adds is_active column to rental_objects
- RoomModal: hide bed type/status/housekeeping in create mode; optional price (from category); restructured Places tab with extra beds constructor
- TariffsPage: auto-generate tariff code from name initials if code field is empty
- types: ExtraPlace.beds for extra place bed configuration

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/migrations/047_rental_is_active.sql

@@ -0,0 +1,5 @@
+-- Add is_active flag to rental_objects (false = template/draft, true = published)
+ALTER TABLE rental_objects ADD COLUMN IF NOT EXISTS is_active BOOLEAN NOT NULL DEFAULT true;
+
+-- Mark all existing objects as active (they were already in use)
+UPDATE rental_objects SET is_active = true;